Control means for dental engines and the like



y 24, 1951 H. M. KECKLEY 2,561,664

CONTROL MEANS FOR DENTAL ENGINES AND THE LIKE Original Filed July 14,1947 IN VEN TOR.

Patented July 24, 1951 UNITED STATES PATENT OFFICE CQNTROL MEANS FORDENTAL ENGINES AND THE LIKE Harold M. Keckley, Findlay, Ohio, assignorto Wm. 0. Ballard, Toledo, Ohio 2 Claims. 1

This invention relates, as indicated, to control means for dentalengines and the like, and more particularly to a foot-operated controldevice of a type adapted to permit considerable freedom of movement onthe part of the operator.

In a co-pending application Serial No. 718,950, filed December 28,l946,'tl1ere is disclosed novel switch-operated means whereby theoperator may control a dental drill or the like merely through theaction of foot pressure upon a resilient elongated tubular member. Asstated in such application, this tubular member may be filled with anyof a variety of fluids, including air, for example. From the point ofview of initial cost and maintenance, air is, of course, ideal butcertain practical problems have been encountered in the use of pneumaticmeans, primarily due to temperature fluctuation. At times when suchpneumatic system has been subjected to relatively high temperaturesthere has been a tendency for suflicient pressure to build up therein toshift the diaphragm to operate the master switch even though suchresilient tubular member has not been subjected to foot pressure. On theother hand, at time of relatively low temperature the pneumatic systemmay become relatively insensitive and difiicult to operate due to thecontraction in volume of the contained air. Both such conditions will,of course, depend upon the temperature at the time the system wassealed. It is very desirable to have a sensitively adjusted pneumaticsystem so that the operation of the dental engine or the like may becontrolled simply by the pressure imposed by one foot of the operator ashe stands by the dental chair.

It is therefore a primary object of my invention to provide controlmeans for dental engines and the like including a foot operatedpneumatic system which will be automatically compensated for ambienttemperature variations.

Another object of my invention is to provide such control means whichwill be rendered inoperative to start the engine when the dental tool orthe like is suspended from its usual support.

Other objects and advantages will become apparent as the followingdescription proceeds.

To the accomplishment of the foregoing and related ends, said invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various ways in which the principle of the invention may beemployed.

In said annexed drawing:

Fig. 1 is a general perspective view of a dental chair and dental engineassociated therewith showing a preferred arrangement of my new controldevice;

Fig. 2 is a diagrammatic layout of one embodiment of my inventionemploying an electric circuit as an element of the control means; and

Fig. 3 is another such diagrammatic layout of a system which ispneumatic throughout.

Referring now more particularly to such drawing, and especially Fig. 1thereof, the master switch I of the motor controlling circuit forelectric motor 2 is installed in the base of dental column 3 in themanner explained in the aforesaid co-pending application, master switchI corresponding to switch I6 of such application. Master switch I is anormally open micro-switch adapted to be operated by movement ofdiaphragm l inres'ponse to pneumatic pressure in chamber 5. Chamber 5 isconnected to a resilient elongated tubular member 8 ordinarily of rubberand sealed at its other end to form a closed system. Such tubular memberwill preferably be arcuately disposed around the base I of the dentalchair 8 and may lie beneath the rubber mat 9 ordinarily placed aroundsuch base.

The tool, such as dental drill I0 mounted on the end of jointed boom I Iis supported when not in use by hook I2 carried by an upper extension ofcolumn 3. As explained in the co-pending application, such hook may bepivotally mounted to operate a switch in an electric circuit controllingthe operation of the motor. The present invention, however, is concernedwith means for controlling the pneumatic system itself.

Referring now more particularly to the Fig. 2 embodiment of myinvention, a valve I3 is provided in tubular member 6 communicating withthe outer atmosphere. An armature I 4 is pivoted at I5 to be rocked uponenergization of solenoid IE to close valve I3. When such solenoid is notthus energized, spring Il acts on the armature to force valve I3 open.Valve I3 may, for example, be an ordinary automobile tire valve. Theenergization of the solenoid is controlled by switch I8 in the upper endof the dental column. Contact member I9 of such switch is forced open bythe end of pivoted hook member I2 when the dental tool is hung upon suchhook, as shown in solid line in Fig. 2. Consequently in this positionsolenoid It will not be energized and valve I3 will be held open so thattubular member 6 is in communication with the outer atmosphere. Footpressure upon such tubular member, therefore, will be ineffective tooperate master switch I when the dental tool is supported upon hook [2.When, however, the operator lifts the tool from such hook, spring 20 iseffective to move the hook into dotted position, as shown in Fig. 2, andspring contact member l9 moves to close switch l8 and activate solenoidl6, thereby closing valve l3. Now that such valve is closed, operationof the dental engine may be initiated and controlled by means of footpressure on member 6, as taught in the aforesaid co-pending application.Obviously the air entrapped in the pneumatic system will normally beunder the same pressure as the outer atmosphere so that micro-switch Imay be set for sensitive response to actuation of diaphragm 4.

Referring now more particularly to Fig. 3 of the drawing, the embodimentof m invention there illustrated is pneumatic throughout with out theemployment of electrical control means. A small tube 2 I, which may beof metal or thickwalled rubber pressure hose is in communication withresilient tubular member 6 and terminates in the upper end of column 3in a valve 22 which may be of the same type as valve 13, for example.When the dental tool is not hung from book l2, spring 20 will, ofcourse, be effective to rock such hook out of engagement with valve 22.When, however, the dental tool is placed upon the hook, rotation of thelatter will be effective to open valve 22 and place tubular member 6 incommunication with the outer atmosphere. It will be seen therefore thatfoot pressure on member 6 will be ineffective to operate master switch Iwhen the tool is hung from hook l2 and the pneumatic system will bautomatically compensated for variations in atmospheric pressure. When,however, the tool is lifted from the hook the pneumatic system is atonce closed and responsive to foot pressure on member 6 to movediaphragm 4 to close switch I It will be seen from the foregoin that Ihave provided control means for dental engines and the like employing apneumatic system in which ambient temperature and pressure changes areautomatically compensated for, and which is rendered inoperative whenthe tool connected to such engine has been hung upon its supportingmeans.

This application is a division of my copending application Ser. No.760,816, filed July 14, 1947, Control Means for Dental Engines and theLike.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims. or the equavalent ofsuch, be employed.

I therefore particularly point out and distinctl claim as my invention:

1. A dental engine, a power operated tool adapted to be driven by saidengine, a movable support for said tool when not in use, pneumaticpressure means operative to control operation of said engine, and a ventfor said pneumatic pressure means including a valve operable by movementof said support when said tool is placed thereon to vent said pneumaticpressure means to the atmosphere.

2. A dental engine including an electric motor, a power operated tooladapted to be driven by said engine, a movable support for said toolwhen not in use, pneumatic pressure means operative to control saidengine, said means having a branch therefrom including a valve operableby movement of said support when said too] is placed thereon to ventsaid pneumatic pressure means to the atmosphere.

HAROLD M. KECKLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,856,869 Grimme May 3, 19322,092,948 Baitinger Sept. 14, 1937 2,444,188 Englund June 29, 1948

